I can't remember exactly, but I think my health nurse told me they are supposed to go from approx 600ml at 12 months to 250ml around the 2 year mark. (250ml being 1 serve of dairy, with 2-3 serves of dairy per day including cheese and yogurt)

750ml is a bit much, but I do know how hard it can be with a fussy kid. I'd suggest only give milk in the morning with breakfast, or before a nap.
And if she is so attached to her milk during the day you will probably have a few days of battles.